Online shopping can be dangerous, and many less technically savvy users have trouble navigating the complicated practice of determining which websites are safe and which aren't. Even otherwise safe websites can be compromised by network attackers. Secure Socket Layer (SSL) connections exist to protect users against network attackers, but understanding the presence and implication of a compromised SSL connection is difficult for inexperienced users. For example, in a browser commonly used today, there may be 13 or more icons and additional possible error messages related to website identity verification.
Even sites with secure network connections may be malicious (e.g., phishing sites) or compromised (e.g., legitimate sites that have been hacked). Site blacklists such as those used by Google Safe Browsing and Zscaler's Safe Shopping identify sites that may be phishing or hacked sites, but this is done separately from any network connection warnings.
Even sites that have secure network connections and are neither entirely malicious nor compromised may be unreliable or untrustworthy.